Polyethylene microporous film for a rechargeable battery separator and a method of preparing the same
OwnerChang Suhinventor
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Abstract
Disclosed are a polyethylene microporous film and a method of preparing the same. The polyethylene microporous film, which has a laminated structure comprising B layer/A layer/B layer, prepared by melt-mixing a polyethylene and an aliphatic hydrocarbon solvent together at controlled mixing ratios to separately form an A layer and a B layer having different porosities, and then coextruding the A and B layers, thus exhibiting excellent mechanical properties, such as strength and elongation, and high-temperature stability. Therefore, the polyethylene microporous film is suitable for use in a rechargeable battery separator.
Claims22
A polyethylene microporous film for a rechargeable battery separator, comprising:
- an A layer formed by melt-mixing 20 to about 40 wt % of a polyethylene with 60 to about 80 wt % of an aliphatic hydrocarbon solvent;
- B layers formed by melt-mixing 45 to about 65 wt % of a polyethylene with 35 to about 55 wt % of an aliphatic hydrocarbon solvent, the B layers are laminated on both surfaces of the A layer;
- and
- the A layer and B layers are coextruded to form a laminated structure comprising B layer/A layer/B layer.
A polyethylene microporous film for a rechargeable battery separator, comprising:
- an A layer formed by melt-mixing 12.8 to about 64.9 wt % of a polyethylene, 0.1 to about 7.2 wt % of a thermoplastic resin incompatible with the polyethylene, and 35 to about 80 wt % of an aliphatic hydrocarbon;
- B layers formed by melt-mixing 20 to about 65 wt % of a polyethylene with 35 to about 80 wt % of an aliphatic hydrocarbon solvent, the B layers are laminated on both surfaces of the A layer;
- and
- the A layer and B layers are coextruded to form a laminated structure comprising B layer/A layer/B layer.
A method of preparing a polyethylene microporous film for a rechargeable battery separator comprising the steps of:
- melt-mixing 20 to about 40 wt % of a polyethylene with 60 to about 80 wt % of an aliphatic hydrocarbon solvent to form an A layer, melt-mixing 45 to about 65 wt % of a polyethylene with 35 to about 55 wt % of an aliphatic hydrocarbon solvent to form B layers, coextruding the A layer and B layers to laminate B layers on both surfaces of the A layer, and then cooling the coextruded layers, to form a gel composition having a laminated structure comprising B layer/A layer/B layer;
- biaxially stretching the gel composition, to prepare a film;
- extracting the aliphatic hydrocarbon solvent from the A layer and B layers of the film using an organic solvent to remove the aliphatic hydrocarbon solvent, to prepare a microporous film;
- and
- heat-treating the microporous film at a temperature not greater than the melting temperature of the polyethylene.
A method of preparing a polyethylene microporous film for a rechargeable battery separator comprising the steps of:
- melt-mixing with 12.8 to about 64.9 wt % of a polyethylene, 0.1 to about 7.2 wt % of a thermoplastic resin incompatible with the polyethylene, and 35 to about 80 wt % of an aliphatic hydrocarbon solvent to form an A layer, melt-mixing 20 to about 65 wt % of a polyethylene with 35 to about 80 wt % of an aliphatic hydrocarbon solvent to form B layers, coextruding the A layer and B layers to laminate B layers on both surfaces of the A layer, and then cooling the coextruded layers, to form a gel composition having a laminated structure comprising B layer/A layer/B layer;
- biaxially stretching the gel composition, to prepare a film;
- extracting the aliphatic hydrocarbon solvent from the A layer and B layers of the film using an organic solvent to remove the aliphatic hydrocarbon solvent, to prepare a microporous film;
- and
- heat-treating the microporous film at a temperature not greater than a melting temperature of the polyethylene.
Dependencies are inferred from the claim text.